Treating rayon cakes



Nov. 25, 1941. HART, JR 2,263,681

TREATING RAYON CAKES Filed Oct. 19, 1938 HIGH FREQUENEY OSCILLATORPatented Nov. 25, 1941 UNITED STATES [PATENT OFFICE izseassi a 'rass'rmcmm cases I George 1'. Hart, in,

United Shoc Mnchln of Flcmington, N. 1.,

Jersey Corporation, Borough a corporation of New Application October 19,1938, Serial No. 285,848

' Claims.

This invention relates to methods of and ap'paratus for treatingmaterial, as, for example, to reduce themoisture content thereof. Theinvention is illustrated in its application to the drying of rayon cakesby a high-frequency electrostatic In the production of artificial silk,yarnof regenerated cellulose is commonly wound in an annular, form,called a cake. While thus packaged. the yarn is subjected to numeroustreatments involving liquid baths, after which the v yamis dried whilestill in the form of a cake.

article inv responseto the amount of moisture therein. i

Another object of theinvention is to devise an improved apparatus forcarrying out the above Most of the ordinary drying processes involve thesubjection of the cakes. at some stage in the procedure, to eithernatural or forced currents,

of warm air. Quite obviously,'this results in the drying of theouterlayers of the cake prior to the inner layers and a decided'disadvantageof this method of treatment lies in the nonuniform shrinking of theyarn. When .the outer layers of the yarn, dryin first, try to shrink,-

the shrinking is restricted by the support provided by the adjacentinner layers, whereas the layers at the-inside of the annulus have anopportunity to shrink all they can. To overcome some of thesedisadvantages, it has been proposed to supply the heat essential forthedrying by a high-frequency electrostatic field which, as iswellrecognized, causes the production of heat throughoutthe article and,therefore, is of material assistance in oflsetting the vuneven shrinkingheretofore encountered. It has been found, however, thatuniformlty ofdryingac tion is dependent on uniformity in the field within thearticle, a state not readily obtained.

such as Bakelite, thereby produ I tion 'of'the heating efiect at thisinner periphery or the rayon cake. 30

treated, this electrode is provided with two pairs of metallic stripsrunning heightwise of the cake With this in mind, one object'of theinvention is to provide an improved methodof drying articles involvingthe subjection of successive portions of the article to the dryingaction of an electrostatic field.

In one aspect, the, invention consists in providing relative rotationbetween the article and an electrostatic field to cause the field topass through successive portions of the article so that uniform heatingis secured and preferably so that the area of treatment is continuallymoving around the center of the article. This may be accomplished eitherby rotating the article with respect to the field or by setting up arotating field within -which the article is positioned.

subjection of a plurality-of articles to individual electrostatic fieldsandthe automatic alteration mounted for rotation about individualelectrodes to the end that thelines offorce of the electro* .staticfield pass substantiallyradially through successive portions of eachcake.

. Experience'shows thatwhile the heating action is well distributedthroughout the cake, a desirable result may be obtained byconcentrating. the heating on the inner periphery of the cake. Inaccordance with another feature of the invention, the inner electrode,which may be cylindrical, is covered with a layer of dielectric,

cing a concentra- In a modified arrangementQan inner electrode isarranged to setup. aseries of stray fields which, by reason of relativerotation produced between these fields and the article, treat thearticle progressively around its center. As illusand the, arrangement issuch that alternate strips are energized from opposite sides'oi' the rsource of high-frequency electric current, there- 40 by to set up afield betweenadjacent strips: .The

direct field between these strips will be contained wholly within theelectrode but, 'at the same time, a stray field will be produced betweeneach pair of electrodes bulging outwardly tlirough the thickness of thecake and producing a heating action the intensity of which is greatestat the interior of the cake, as is desirable.

In, the practice of the inventionythere is no assurance that the amountof moisture contained within a plurality of cakes will be uniform and ifall' the cakes are subjected to the Fromanother aspect, the inventioninvolves the of the intensity of the field of'any individual treatmentof the drying apparatus for an equal time, the consequence will be thatthe desired degree of moisture will be reached in some cakes sooner thanin others; it being understood that commonly it is 'not desired toremove all the moisture but rather to bring it down to a certainpredetermined minimum at which the yarn may be handled to best advantagein later operations. To this end and in accordance with another featureof the invention, apparatus is provided which is responsive to theamount of moisture in the article and is designed to vary the intensityof the field when the moisture reaches a predetermined degree. A simplearrangement for this purpose is illustrated herein, in which the weightof each cake is balanced against the compression of a spring, thereaction ot which is preferably made adjustable, and the arrangement issuch that when the cake becomes light enough, the spring will liftitand, in so doing, will operate to interrupt the coupling between theinner electrode and one sideof the source of electricity.

These and other features of the invention will be best understood from aconsideration of the following specification, taken in connection withthe accompanying drawing, in which? Fig. 1 is an elevation, with partsbroken away and in section, of apparatus for treating a-single cake ofrayon and including an automatic arrangement for breaking the couplingwhen desired;

Fig. 2 is a similar view, partly in section, along the line II--II ofFig. l and showing a conveyer arrangement for supporting a series ofcakes for movement with respect to one'of the electrodes;

Fig. 3 is an angular view with parts broken away and in section of amodified cake-supporting device having an inner electrode arranged toproduce a plurality of stray fields;

Fig. 4 indicates diagrammatically an electrostatic field passingradially through a portion of an annular article which is rotatedthrough this such as a rayon cake l6, provision is made ifor supportingeach individual article on a carrier i2, provided with a plurality ofgrooved rolls l4 for mounting the carrier on parallel bars I6. It willbe understood that the bars l6 extend a substantial distance along thedrying chamber and that means, not illustrated, is provided for mov- Iing the successive carriers 12 along these bars.

An arrangement suitable for the purpose is illustrated in Letters Patent'of the United States No. 2,132,362, granted October-4, 1938, on anapplication of J. E. Regan. V

Extending parallel to the conveyer bars is an electrode plate 26 mountedon a suitable support 22 by an insulator 24 and connected at 26 to oneside of a high-frequency oscillator 36, to which electric current of lowfrequency is supplied through the terminals 32. The other side of theoscillator is connected at 34 to a narrow po'wer rail or bus-bar 36mounted on the support 22 by an, insulator 36. Associated with the bar,to form a coupler acting electrostatically, is a pickup 46 which isconnected to an inner electrode 42. The pick-up 46 and the bar 36,acting as parts of a condenser, transfer the-current electrostatically.I This inner electrode is cylindrical and is surrounded by a layer ofdielectric 44, such as Bakelite or the like. By this arrangement eachindividual cake is positioned in an electrostatic field, such as isillustrated diagrammatically in Fig. 4, which passes radially throughthe hollow article l6 between the inner electrode 42 and the electrodeplate 26.

It will be understood that once the cakes have become heated, they donot cool immediately, even if the electric field does not traverse themcontinuously. Trials, for example, have been conducted in which thetemperature ranged from 126 F. on the inside of the cake'to 68 F. on theoutside and the oscillator was operated at a frequency of about fifteenmegacycles. Under these conditions, it is not essential that theelectrode 26 extend the whole length of the conveyer because the dryingaction will continue in the heated cakes for some time after they passout of the field. v

A conveyer arrangement is also desirable in that it facilitates therotation of work supports comprising an upper table 56 loosely joined bya pin 52 to a lower table 64. Theupper table is provided with aplurality of radial ribs 56 to permit a free circulation of air and theescape of moisture. face 68 resting against one of the conveyer bars I6so that rotation is effected by this frictional contact as the carriersl2 are moved. These table supports are preferablymade of dielectricmaterial, such as Bakelite, and are supported for rotation about aspindle 66 held in upright position in a bracket 62 attached to thecarrier I2,

with its axis parallel to the surface 'of the elec'-' This bracket hasan upper arm 64 rotatable within a bushing 16 in the upper arm 64. Aspring 12 surrounding this sleeve 68 bears against a washer at the underside of the upper I arm 64 and against a collar held on the sleeve by aset screw thereby, by its expansion, holding the conical surface 56 ofthe table 54 in firm frictional contact with the upper bar l6. The uppertable 56 is supported on 'a shoulder 16 of the spindle 66 and thereduced upper end of the spindle is pinned to a block H at thebottom ofthe inner electrode 42 and is arranged to contact with a spring 16attached to said electrode 42. The lower end ,of the spindleis forkedand rests on a spring-operated latch arm 86 pivoted in the lower arm 66of the bracket, the outer end of this arm 86 being notched to contactone end of the pick-up, 46. Pivoted to the outer end of the arm 66 is arod 62 extending upwardly through the outer, end of the arm 66 andsurrounded by a spring 64, the compression of which may be adjusted bynuts 86. When the weight of the rayon cake I6 is reduced to a certainpoint by evaporation of moisture therefrom, the spring 64 will liftthe'arm 66 and, with it, the spindle 66 and the upper table 56, on whichthe cake is supported. This movement of the latch. arm 66 will disengagethe end of the arm bushing 16 contacts with,the sleeve 66- and the.

sleeve 66 contacts with the spindle 6 6, thereby providing an electriccircuit from the pick-up 46 to the spring 16 on the inner electrode 42.When the arm 66 is raised by the spring 84, the

pick-up 46 is allowed to swing downwardly about the pivot 62, thusbreaking theelectrostatic cou- I'he lower table has a conical sur--claim as new and desire to secure by Letters pling with the bar II. Itthus appears that when the rayon cake reaches the desired degree ofdryness, the electrostatic field passing between the electrode 42 andthe plate electrode 20 will be removed, permitting a cessation of thedrying action.

In the modified electrode arrangement illustratedin Fig. 3, a table lilis movable with a lower table I which rests against a conveyer bar Itand, having a sleeve I, is freely rotatable about a spindle I 60 whichis supported in a carrier I! just as is the spindle O in Fig.1. Thisspindle I" is connected to one side of the oscillator through a pick-upII in nontouching but adJacent relation to a power rail 36 which isJoined to one side of the oscillator. be understood that the current istransferred from this rail to the pick-up by electrostatic coupling. l

Supported within a recess III 'in the table I" is an electrodearrangement involving a cylinder I02 of Bakelite or the like having atits lower end a Bakelite block 104 fastened by a transverse pin to thespindle I60 and inwhich are supported a pair of upstanding electrodebars I, I08.

" and-causing relative rotation between the article Itwil1- between theinterior of the cake and the outside These are connected electrically toeach-otherv and to the spindle I60 by a metal connector IIO. Spaced by90 from these electrodes III and it are other electrode bars Ii! and Illhaving a common plate H6 which underlies a power rail l20 Joined by awire I28 to one side of an oscillator. To insure a proper pick-up byelectrostatic, i. e. condenser, coupling with the power rail I20, theplate H0 is provided with extensions I22 and I24 elongated in thedirection of the length of the power rail and hinged to the plate 8,thereby to facilitate the application or removal of cakes of rayon asthey are threaded over the cylinder M2 at some point beyond the end ofthe rail I20. Between each twoadjacent electrodes I06 and H2, H2 andI08, etc., there is.

set up an electrostatic field.- The direct field passing through theshortest distances between these adjacent electrodes will havepractically no effect on the cake surrounding the electrode cylinderI02. On the other hand, stray'fields (Fig. 5) bulging out between eachtwo adjacent electrodes will act onthe annular cake which, foruniformity of drying action, will be rotated with respect to'thesuccessive strayfields to produce a complete drying by the resultantintegrating action of the stray fields. The intensity of these fieldswill be, as desirable, greatest at the inner periphery of the annularcake and of lessening intensity toward the outer periphery thereof.

In the use ofthe apparatus'in'carrying out the novel method, rayon cakeswill be positioned on the tables and the arms 00 will be latched overthe pick-up 40, these having been swung into the position. illustratedin Fig. 1. It is assumed that the compression of the springs 84 has beenadjusted to the desired degree by turning the nuts 86. A series of cakeshaving thus been positioned on the tables mounted on the conveyer,electric current will be supplied to the oscillator and a drying actionset up which will be continued so long as may be necessary, until allthe cakes have been reduced in weight to such a degree that the springsM have been able to lift the upper tables 50, allowing the pick-ups l0and their supporting arms 90 to drop to a substantially verticalposition away from the Patent of the United States is:

subjecting it to an electrostatic field existing be.- tween twoelectrodes which consists in positioning the article to surround one ofthe electrodes, and then causing relative rotation between the articleand the inner electrode,

' 2. That method of treating a hollow article by subjecting it to anelectrostatic field existing between two electrodes which consists inpositioning the article to surround one of the electrodes,

and the outside electrode.

3. That method of treating a hollow article which consists in rotatingthe article about an axis thereof and passing anelectrostatic fieldsubstantially radially through one side only of the-hollow article. 7

4. That method of drying hollow rayon cakes which'consists in creatingan electrostatic field thereof, and inrotating the cake to cause-thefield to act on successive portions of the same.

5. That method of treating a hollow "article which consists in producinga stray electrostatic field bulging toward and intersecting a side ofthe article, and causing relative rotationbetween the field and thearticle.

'6. That method of drying a plurality of rayon cakes which consists inpassingv an electrostatic field through at least a portion of each cake,and automatically shutting off the field through any individual. cake inresponse to change in the weight of the same. i

-7. In an apparatus for drying articles of annular shape, electrodespositioned within and without said annular article, means for producingan electrostatic field between said electrodes, and means for producingrelative rotation between the article and one of said electrodes.

' 8. In an apparatus for drying annular rayon cakes, a conveyer for aseries of cakes, an electrode common to a plurality of cakes andpositioned beside the conveyer,, a series of electrodes positioned onewithin each cake whereby elec-- trostatic fields are set up-which passradially through the cakes, means for rotating said cakes upon the.conveyer, and means for connecting said series of electrodes to one sideof a source of high-frequency current and said common electrode to theother side thereof.

9. In an apparatus for drying an article of' annular shape, asubstantially fiat plate electrode 7 positioned adjacent to the outercircumference of the article, an electrode positioned within theplurality of cakes and positioned beside the conveyer adiacentto theperiphery of the cakes, a series of electrodes positioned one withineach cake whereby electrostatic fields are set up which pass radiallythrough the cakes, and means forenergizing said electrodes.

11. In an apparatus for drying articles by an electrostatic field.- aconveyer for supporting a series of said articles, a bus-bar alongsidesaid conveyer, means for electrically connecting said bus-bar to oneside of a source of current, a plate electrode elongated in thedirection of movement of the conveyer and positioned alongside thelatter, means for electrically connecting said plate electrode to theother side of said source, an electrode on the conveyer, a depressiblearticle support for positioning an article on the conveyer in the fieldset up between the latter electrode and said plate electrode,an'individual coupler movably supported on the conveyer and interposedbetwenthe electrode on the conveyer and the bus-bar, a latch holdingsaid coupler in operative relation to the bus-bar, a spring forreleasing the latch and hence the coupler to permit the couplingprovided thereby to be broken irrespective of the position of theconveyer, and a connection between said depressible article support andsaid spring.

12'. In an apparatus for drying moist articles by an electrostaticfield, a conveyer for'supporting a series of articles, individualelectrodes on the conveyer for at least some of the articles thereon,means for transmitting energy from one side. of a source of current tosaid electrodes including individual pick-up devices carried by theconveyer with said electrodes, another electrode connected to the otherside of said source and cooperating with said first electrodes to pass afield through each article, and spring-upheld means supporting one ofsaid articles on said conveyer and operated, as a result of the loss ormoisture in the article, to render an associated pick-up deviceinoperative to transmit energy when a predetermined degree of moistureis obtained.

13. In an apparatus for drying aseries'oi' articles, an electrode commonto a plurality of said articles, means for connecting the commonelectrode to on side of a source of electricity, in-

- dividual electrode i'orsaid articles,.displaceable individual couplingdevices for connecting said latter electrodes to the other side of saidsource, yieldable means supporting an article in an electrostatic fieldproduced between said common electrode and an individual electrode, andmeans operated by said supporting means as a result of the lossof-moisture from the article to act upon the displaceable couplingdevice to electrically disconnect said individual electrode for saidarticle from said source.

14. In an apparatus for drying rayon cakes, a conveyer having aplurality of supports for said cakes, electrodes on the supports andpositioned within the cakes, means for rotating said supports, a plateelectrode extending beside the conveyer and adjacent to the peripheriesof the cakes, means for connecting said plate electrode to one side of asource of high-frequency current,"

a bar extending along the conveyer and spaced a substantial distancefrom the plate electrode, means for connecting said bar to the otherside of said source, and means for conducting current between said innerelectrodes'and said bar inw ciuding individual pick-ups displaceablymounted on the conveyer.

15. In an apparatus for drying rayon cakes, a conveyer, a plurality ofsupports thereon for said cakes, an electrode on each support andpositioned within its cake, a plate electrode extending beside theconveyer and adjacent to the peripheries o! the cakes, means forconnecting said plate electrode to one side of a source oi.highfrequency current, a bar extending parallel to said electrode andspaced a substantial distance therefrom, means for connecting said barto the other side of said source, individual pick-ups between said innerelectrodes and said bar, and means for rotating the individual supportsas the conveyer moves.

16. In an apparatus for drying rayon cakes, a conveyor, a plurality 01supports thereon !or said cakes, an electrode on each support andpositioned within its cake, a plat electrode extending beside theconveyer and adjacent to the peripheries of the cakes, means forconnecting said plate electrode to one side of a source of highirequencycurrent, a barextendingparallel to said electrode and spaced asubstantial distance therefrom, means for connecting said bar to theother side of said source, individual pick-ups between said innerelectrodes and said bar, and means associated with eachsupportresponsive to the weight of the cake carried thereby forrendering inoperative the connection between its pick-up and the barwhen the moisture content of a cake reaches a predetermined amount.

1'7. In an apparatus for drying rayon cakes, a support for a cake, aplurality of electrodes positioned within a cake, and means forconnecting alternate electrodes to opposite sides of a source ofhigh-frequency electric current,

18. In an apparatus for drying rayon cakes, a rotatable support, acylindrical member of dielectric material separately supported adjacentto the center of said support, metallic strips extending heightwise ofthe cylinder, and means for connecting alternate strips-to oppositesides of a source of high-frequency electric current.

19. In an apparatus for drying annular rayon cakes, a support,electrodes positioned 'adjacent to said support and within a cake,means'ior connecting alternate electrodes to opposite sides of a sourceof high-frequency electric. current,

, and means for causing relative rotation between the support and theelectrodes. A r

20. In an apparatus for drying annular rayon cakes, a support providedwith transversely ex- I tending ribs, an electrode positioned at a midpoint of said support and over which a cake may be threaded to positionit onthe support, and

.means co-operating with said electrode to create an electrostatic fieldpassing substantially radially through at least a portion of thecake.

GEORGE T. HART, JR.

